Alkali metal conductor terminal



Oct. 3, E967 N. E. M NERNEY 3,345,453

ALKALI METAL CONDUCTOR TERMINAL Filed Feb. 18 1966 FE G. 5

74 I l l I N VEN TOR.

NORMAN E. McNERNEY ATTORNEYS United States Patent 3,345,453 ALKALI METAL CONDUCTOR TERMINAL Norman E. McNerney, Hampden, N.H., assignor to Simplex Wire and Cable Company, Cambridge, Mass., a corporation of Massachusetts Filed Feb. 18, 1966, Ser. No. 528,496 2 Claims. (Cl. 174-77) The present invention relates to conductor terminals and in particular to a terminal suitable for use with conductors made of alkali metals, alkaline earth metals and alloys and mixtures thereof.

Conductors made of alkali metals, alkaline earth metals, their alloys and mixtures present termination problems not previously encountered and, therefore, terminals and joining techniques heretofore generally known are not suitable for use with these conductors. Because of the high reactivity of the metals involved, conductors made of them must be protected from the atmosphere, as by enclosure in a tubular sheath in the case of elongated, condoctors, and the conductor terminal must be adapted to aid in this protection. The low tensile strength of these conductor metals, moreover, reduces their ability to form an efiective mechanical bond with the terminal and alternate bonding methods must be resorted to.

It is, therefore, an object of the present invention to provide a terminal for sheathed conductors wherein the conductive metal is an alkali meal, alkaline earth metal, or an alloy or mixture thereof, which terminal incorporates a sealing arrangement whereby the conductor metal is protected from the atmosphere and which terminal is affixed mechanically to the conductor sheath.

This and other objects of the invention are accomplished by providing a terminal for an elongated conductor having a tubular protective sheath in which the terminal includes a plug, a sleeve and a coupling nut. The plug has a contact portion at one end which is sized to fit into an end of the tubular sheath for the conductor, displac ing the conductor metal. An intermediate portion of the plug is shouldered to limit movement of the plug into the sheath and against which the end of the sheath is flared outwardly. The sleeve is sized to fit over the sheath positioned with an end of the sleeve butting against the flared end of the sheath such that the end of the sheath is received between such end of the sleeve and the shouldered portion of the plug. The nut is received over the sleeve and the portion of the plug extending away from the end of the sheath and engages the sleeve and plug to restrain their movement apart from each other in order that the sleeve and plug firmly retain the flared end of the sheath.

For a fuller description of the present invention reference is made to the appended drawings of which:

FIG. 1 is a longitudinal section of a terminal constructed according to the present invention positioned in the end of a sheathed conductor and FIG. 2 is an elevation partly in section of a splice constructed according to the present invention joining a pair of sheathed conductors.

Referring more particularly to FIG. 1 a sheathed conductor is shown formed of an elongated metallic conductor 12 of sodium or other electrically conductive alkali metal, alkaline earth metal or an alloy or mixture thereof and a tubular conductor sheath 14 which completely surrounds and encases conductor 12. Sheath 14 is typically aluminum or copper but can be other metals such as lead, iron, stainless steel or the like. Sheath 14 can also be made of a dielectric or other solid material, provided the material has the requisite mechanical properties to permit secure connection with it. A terminal 16 is shown attached to the end of sheathed conductor 10 consisting of a sleeve 18, a coupling nut 20 and a plug 22, all made preferable of the same metal as sheath 14, when it is metal.

Sleeve 18 is a hollow cylinder with an inside diameter slightly greater than the outside diameter of Sheath 14- Sleeve 18 can be considered in two sections for more clear description, namely, a first section 26 of relatively thin, constant, wall thickness extending from one end 24 of sleeve 18 for about one-half of its length and a second section 28 which has a relatively thicker wall thickness and includes an outwardly sloping inner edge 30 at its end 32 remote from section 26. Sections 26 and 28 which have the same inside diameter are integrally joined together at approximately the center of sleeve 18, their junction forming a shoulder 34 at right angles to the axis of sleeve 18. An annular groove 36 is provided about the inner wall of section 28 slightly removed from sloping edge 30, and an O-ring 38 is positioned in groove 36 to provide a seal between sleeve 18 and sheath 14 over which sleeve 18 is received in a sliding fit.

Plug 22, which functions as a contacting and connecting element, is electrically conductive and includes a contact portion 40 which is somewhat cylindrical and hollow, its free or leading edge 42 being pointed to facilitate insertion into the end of a cable. The internal wall surface 45 surrounding the hollow center of contact portion 40 provides sufi'icient area between plug 22 and conductor 12 to insure an efficient electrical joint. Plug 22 also includes a shouldered intermediate portion 44 of gr ually increasing diameter, the diameter of which increases from slightly less than the inside diameter of sheath 14 to a diameter greater than the inside diameter of sleeve 18.

Immediately adjacent portion 44 plug 22 includes an externally threaded portion 47 for a substantial distance along its length and having a minor diameter slightly larger than the outside diameter of section 28 of l ve 18. Beyond portion 47, plug 22 is relatively smooth terminating in an end face 46 which has rounded edges and includes a lug 48 at itscenter. Lug 48 is conventional and includes apertures 50 and 52 for the purpose of establishing mechanical and electrical connection thereto. Other forms of connectors can be substituted for ing 48.

Coupling nut 20 is hexagonal and hollow, its length being approximately equal to the combined lengths of sleeve 18 plus the threaded portion 47 of plug 22. The hollow interior of coupling nut 20 is formed of three interconnecting axially aligned sections 54, 60 and 62.

First interior section 54 is cylindrical, having a diameter slightly greater than the outside diameter of section 26 of sleeve 18 and a length approximately equal to that of section 26 terminating at one end in the end face 49 of nut 20. Section 54 includes an annular groove 56 about its internal surface in which an O-ring 58 is seated to provide an internal seal between collar 20 and sleeve 18.

Second section 60 within nut 20 is cylindrical, having a diameter slightly greater than and a length approximately equal to that of section 28 of sleeve 18. Section 60 is located in the center of nut 20 and connects section 54 with the third section 62. The junction of sections 54 and 60 forms a shoulder 57 extending at a right angle to the axis of nut 20.

The third section 62 within nut 20 is cylindrical and threaded, its minor diameter being slightly greater than the outside diameter of section 28 of sleeve 18. The inter nal threads of section 62 correspond to the external threads of portion 47 of plug 22. Section 62 extends from section 60 to the other end 51 of nut 20. At a point adjacent end 51, an annular groove 64 is formed in the threaded internal surface of section 62, and an O-ring 66 is positioned therein to provide a seal between coupling nut 20 and plug 22. O-ring 66 is made from an easily deformable material and the external threaded on portion 47 of plug 22 penetrates into O ring 66 deforming it to create the desired seal.

In connecting terminal 16 to conductor coupling nut 20 is first slipped, end 49 first, over sheathed conductor 10 and moved along its axis. Sleeve 18 is then drawn, end 24 first, over the end of sheathed conductor 10 and positioned within nut 20 so that section 54 of nut 20 registers with portion 26 of sleeve 18 and shoulder 57 of nut 20 abuts shoulder 34 of sleeve 18. The contact portion 40 of plug 22 is then forced into the end of sheathed conductor 10 until portion 44 engages the end of sheath 14 expanding it to a diameter greater than the inside diameter of sleeve 18.

Coupling nut 20 and sleeve 18 are then drawn along the axis of sheathed conductor 10 toward its end until threaded section 62 of nut 26 engages the externally threaded portion 47 of plug 22. Thereafter nut 20 is rotated threadedly and sealingly to engage plug 22 and to urge the sloping forward edge 30 of sleeve 18 against the expanded end of sheath 14. The end of sheath 14 is thus tightly held between edge 30 of sleeve 18 and portion 44 of plug 22 thereby creating an effective mechanical bond between terminal16 and sheath 14.

In FIG. 2 a splice 67 is shown incorporating a pair of back to back terminals 68 and 70 each similar in construction to terminal 16 of FIG. 1. Those portions of splice 67 which are identical to the corresponding portions of terminal 16 of FIG. 1 are identified by the same reference numerals, a being used to distinguish portions of terminal 70 from those of terminal 68. As will be seen the only difference between the splice of FIG. 2 and a pair of terminals such as that shown in FIG. 1 is that a single contacting and connecting element 72 is provided interconnecting the terminals 68 and 70 and having a hexagonal central portion 74 to facilitate gripping.

The connection of splice 67 to each of sheathed conductorsv 10, 10' is successively accomplished as described above with reference to the connection of terminal 16 of FIG. 1 with a single conductor 10.

The connection of terminal 16 to conductor 10 or of splice 67 to sheathed conductors 10 and 10 can be facilitated by heating of the contacting and connecting elements, 22 and 72 as disclosed in co-pending application of 4 Kenney for Method of Cable Termination, Ser. No. 520,- 755 filed Jan. 14, 1966. Contact with the conductive metal can be improved by coating elements 22, and 72 with mercury as disclosed in co-pending application of Feick et al., Ser. No. 480,480, filed August 17, 1965, or with tin.

It will be noted with reference to the drawings that the hollow portions of plugs 22 and 72 exetnd beyond their contact portions 40, i.e. beyond the point of maximum penetration into the conductor. These hollow portions of the terminals are filled by metal which is displaced from the conductor as the terminal is inserted into its end. Alternately, a passage through elements 22 and 72 can be provided through which the displaced metal can escape which passage is then cleaned out and sealed as by filling with a low melting alloy after insertion is complete.

I claim:

1. A terminal for an elongated conductor made of an alkali metal, an alkaline earth metal, or an alloy or mixture thereof, which conductor is encased in a tubular sheath, said terminal including a sleeve, a plug, and a coupling nut, said sleeve being positioned over said sheath adjacent an end thereof, said plug having an end portion positioned within said end of said sheath in electrical contact with said conductor, said plug further including an intermediate shouldered portion positioned adjacent said end of said sheath with said end of said sheath flared outwardly between the adjacent end of said sleeve and said shouldered portion, said coupling nut being positioned over said sleeve and plug in engagement therewith to hold said sleeve end and shouldered portion of said plug against said end of said sheath.

2. A terminal according to claim 1 in which said nut is threadedly engaged with one of said sleeve and said plug.

References Cited UNITED STATES PATENTS 6/1962 Connell 17477 X 8/1965 Johnson et al. 33910 0 

1. A TERMINAL FOR AN ELONGATED CONDUCTOR MADE OF A ALKALI METAL, ALKALINE EARTH METAL, OR AN ALLOY OR MIXTURE THEREOF, WHICH CONDUCTOR IS ENCASED IN A TUBULAR SHEATH, SAID TERMINAL INCLUDING A SLEEVE, A PLUG, AND COUPLING NUT, SAID SLEEVE BEING POSITIONED OVER SAID SHEATH ADJACENT AN END THEREOF, SAID PLUG HAVING AN END PORTION POSITIONED WITHIN SAID END OF SAID SHEATH IN ELECTRICAL CONTACT WITH SAID CONDUCTOR, SAID PLUG FURTHER INCLUDING AN INTERMEDIATE SHOULDERED PORTION POSITIONED ADJACENT SAID END OF SAID SHEATH WITH SAID END OF SAID SHEATH FLARED OUTWARDLY BETWEEN THE ADJACENT END OF SAID SLEEVE AND SAID SHOULDERED PORTION, SAID COUPLING NUT BEING POSITIONED OVER SAID SLEEVE AND PLUG IN ENGAGEMENT THEREWITH TO HOLD SAID SLEEVE END AND SHOULDERED PORTION OF SAID PLUG AGAINST SAID END OF SAID SHEATH. 